In such devices, the rolled-up portion generally comprises a long narrow paper tube, closed at one end, which is of flat section in the rolled-up state and held in the rolled-up state by means of a wire spring which extends the length of the tube. As air is delivered to the tube by way of the mouthpiece the tube is inflated and thereby unrolled to a fully extended position against the inherent spring resilience of the wire spring. Often the mouthpiece includes a pivotable diaphragm so that the unrolling action of the tube is accompanied by a kazoolike sound made by the air issuing past the diaphragm. On cessation of the delivery of air to the tube, the tube collapses and is returned to its original rolled-up state by way of said wire spring. The intentioned effect of the device is to induce surprise or joviality, usually in an unsuspecting observer. However, such devices have been in existence for many years and although they still may retain an element of fun such devices are well known so that their effects are not entirely unexpected, thereby,disadvantageously, tending to reduce the element of surprise or joviality and thereby, disadvantageously, tending to reduce the enjoyment level of the device.
It is an object of the present invention to alleviate one or more of the aforementioned disadvantages and/or to provide a practical joke device having a somewhat different or additional effect to the surprise effect already mentioned.